OK, let's work through this together. We're starting with 521 and we're going to multiply it by 48, which means we add 521 to itself 48 times.
Step 1: 0 + 521 = 521
Step 2: 521 + 521 = 1042
Step 3: 1042 + 521 = 1563
Step 4: 1563 + 521 = 2084
Step 5: 2084 + 521 = 2605
Step 6: 2605 + 521 = 3126
Step 7: 3126 + 521 = 3647
Step 8: 3647 + 521 = 4168
Step 9: 4168 + 521 = 4689
Step 10: 4689 + 521 = 5210
Step 11: 5210 + 521 = 5731
Step 12: 5731 + 521 = 6252
Step 13: 6252 + 521 = 6773
Step 14: 6773 + 521 = 7294
Step 15: 7294 + 521 = 7815
Step 16: 7815 + 521 = 8336
Step 17: 8336 + 521 = 8857
Step 18: 8857 + 521 = 9378
Step 19: 9378 + 521 = 9899
Step 20: 9899 + 521 = 10420
Step 21: 10420 + 521 = 10941
Step 22: 10941 + 521 = 11462
Step 23: 11462 + 521 = 11983
Step 24: 11983 + 521 = 12504
Step 25: 12504 + 521 = 13025
Step 26: 13025 + 521 = 13546
Step 27: 13546 + 521 = 14067
Step 28: 14067 + 521 = 14588
Step 29: 14588 + 521 = 15109
Step 30: 15109 + 521 = 15630
Step 31: 15630 + 521 = 16151
Step 32: 16151 + 521 = 16672
Step 33: 16672 + 521 = 17193
Step 34: 17193 + 521 = 17714
Step 35: 17714 + 521 = 18235
Step 36: 18235 + 521 = 18756
Step 37: 18756 + 521 = 19277
Step 38: 19277 + 521 = 19798
Step 39: 19798 + 521 = 20319
Step 40: 20319 + 521 = 20840
Step 41: 20840 + 521 = 21361
Step 42: 21361 + 521 = 21882
Step 43: 21882 + 521 = 22403
Step 44: 22403 + 521 = 22924
Step 45: 22924 + 521 = 23445
Step 46: 23445 + 521 = 23966
Step 47: 23966 + 521 = 24487
Step 48: 24487 + 521 = 25008

So, 521*48 = 25008